Today, the test and measurement of telecommunications networks plays a vital role in achieving the high level of system availability required by the end user. Particularly in the field of data communications, companies need a system with little or no down time. In order to achieve a high level of system availability, it is necessary to isolate the network problem and repair or replace the faulty components in minimal time. This requires evaluating the entire network with sufficient test capability to isolate the problem quickly.
The configuration of every network is different and, therefore, isolating the problem the first time can prove difficult. With a variety of transmission technologies, from digital to analog and a wide range of frequencies, plus the many types of links that are utilized, such as voicegrade circuits and carrier facilities within the network, an extensive repertoire of test functions is required.
Today, total network testing can be broken down into four basic areas: protocol testing, digital transmission testing, signaling/supervision, and analog transmission testing. Protocol testing is applicable over the entire telecommunications network. Digital transmission testing and signaling/supervision activities cover the complete network with the exception of the terminal equipment and modem interfaces. Analog transmission testing is specific to carrier facility links.
In the prior art, evaluation of these four areas required separate pieces of test and measurement equipment, each utilizing at least one essential instrumentation package. For example, transmission impairment measuring sets (TIMS) provide analog test capabilities such as measurement of level/frequency, signal-to-noise, envelope delay, intermodulation distortion, phase and amplitude jitter, P/AR, and return loss.
Signaling/supervision test sets provide the supervisory and address signaling functions needed to access and control different types of transmission circuits. Protocol analyzers perform monitoring, recording, trapping, emulating, and analyzing functions at the physical data link and network protocol levels.
Digital transmission, or pulse code modulation (PCM), test sets provide for dropping and inserting signals from and into the PCM pulse train, measurement of bipolar violations, frame synchronization, and signaling bit status. Frequency selective level meters enable numerous routine tests to be performed over a wide range of frequencies, from voiceband up through "group" frequencies.
All of this test and measurement equipment is essential in the process of testing and isolating problems within the complete network.
For maintenance or service personnel, testing a network is a big job. When faced with a faulty network and the pressures to get back on-line, they have two choices. They can attempt to deduce where the problem lies from information given by the end user and risk taking only one or two pieces of test equipment along with them. On the other hand, if they have little or no information about the problem, they must take as much equipment as they can carry.
The job would be significantly easier if each piece of test equipment could perform several test functions. It would be better still if all the functions required to test a complete telecommunications network could be incorporated into one unit. A single package is easier to carry and lighter than several instruments. A single instrument will also be less costly if it performs multiple tests yet only has a single housing, single power supply and single display.
Technology is at a stage where total network testing with a single package is possible by imaginatively exploiting the computing power of a microcomputer or processor. By adding multiple test function capabilities to a basic computer package, it is possible for a single unit to provide all the functions necessary to test a complete telecommunications network and to provide computer power as well.
Many features of the computer are highly complementary to the field of network testing. A computer driven device can have an integrated screen or display, a feature which has been offered in individual test sets presently available. In the subject system, where many tests are combined in a single package, the computer makes it possible to arrange the screen formats to be relatively consistent for each test. In this way, a single technician can be rapidly taught to perform a variety of measurements. Computer-based instrumentation also allows entry level technicians to perform complex test functions. Parameters, limits, and conditions of a sequence of tests can be programmed ahead of time by a senior technician. All the trainee needs to do is hook up the instrument to the line and, in the simplest configuration, press a single key to start the test sequence.
Another advantage of a computer-based instrument is that by utilizing self-diagnostics, the device can take care of its own maintenance in a fraction of the time it would take a service technician. Many selfdiagnostics programs take only seconds to run and can be activated each time the instrument is turned on.
A computer-based instrument is also advantageous in that administrative processes of a service organization can be controlled. Rather than having service personnel fill out lengthy reports detailing trouble and solutions, with the help of administrative software, the test results can be stored in the device and transferred to a central office electronically.
Many of today's test devices incorporate one or more microprocessors, but often only to replace existing discrete digital components. While this results in the simplifying of manufacture, and the reduction of cost to the buyer, the operation and function of these test devices do not differ substantially from that of their predecessors. These systems in most part fail to exploit the computing power of the microcomputer.
In contrast, in the subject invention, a true use of the computing power of microcomputers and microprocessors is made, to the point where the operating capabilities of the processors used are pushed to their limit. The subject invention employs a unique system architecture to provide each of the four basic areas required for total network testing in a single microcomputer based unit. In such architecture the processors take on many roles and preform a variety of functions. Because the computer architecture, changes, modifications and corrections in the testing functions can be easily and simply implemented by way of a software change, e.g. such as by changing the program on a floppy diskette. Further, test functions can be added easily and simply by modifying the programs on a diskette or adding additional programming by way of diskette.
Accordingly, it is an object of the subject invention to provide a new and improved piece of test equipment which can perform multiple types of telecommunication network measurements.
It is a further object of the subject invention to provide a multiple test device wherein the display function associated with each test is arranged with a consistent format to facilitate operation.
It is another object of the subject invention to provide a new and improved multiple test device having a novel architecture.
It is still a further object of the subject invention to provide a new and improved multiple test device wherein processing functions are shared among various microprocessors to increase computing speed.